In recent years, one of the major concerns in hair-care products is improvement in hair damages on surface of hair (cuticle), caused by outflow of internal lipids and the like due to chemical treatments including hair colors and permanent waves, and physical treatments including blowing; that is, for example, prevention of lifting up of cuticle, improvement in hair strength and smoothness, and prevention of hair dryness.
To improve conditions of damaged hair, there has been conventionally proposed a method to supplement an appropriate amount of oil to hair to provide the hair with smoothness and flexibility, by means of combining a plant oil such as camellia oil and olive oil to hair cosmetics.
Furthermore, to improve comfortable sensation upon use of hair cosmetics, concomitant use of silicone oils and their derivatives such as high-molecular-weight silicone oils and volatile silicone oils has also been proposed.
Moreover, to improve comfortable sensation upon use, concomitant use of ester oils such as diethoxy ethyl succinate has been proposed; also, aromatic alcohols such as benzyl alcohol have been used as a penetration-enhancing agent for oil agents.
However, when a plant oil alone is used as an ingredient of hair cosmetic materials for caring damaged hair, uncomfortable stickiness accompanies upon application to hair, and a heavy finish is also imparted; therefore, an entirely satisfactory hair cosmetic material could not be obtained.
Furthermore, even when a silicone oil is co-used, although a light refreshing finish is imparted, an improvement in hair strength is not sufficient, and unnatural shine deteriorates the hair appearance upon its application; thus, an entirely satisfactory hair cosmetic material could not be obtained in this case as well.
Moreover, concomitant use of conventional ester oils is not satisfactory from the viewpoint of improvement in sensation upon use, in addition to the problem of deteriorated storage stability. When aromatic alcohols are used as a penetration-enhancing agent, there is a problem of odor and safety, etc.; thus, an entirely satisfactory hair cosmetic material could not be obtained in this case as well.
For example, to improve sensation upon use, an oil-based hair cosmetic material formulated with a volatile hydrocarbon oil, a plant oil, and dimethiconol has been proposed (Patent Literature 1). To improve the effects of care for damaged hair and sensation upon use, a hair cosmetic material formulated with dimethyl polysiloxane and a hydrocarbon oil, etc. (Patent Literature 2), and an oil-based hair cosmetic material formulated with polyurethane polymer, a silicone oil and a nonionic surfactant, etc. (Patent Literature 3) have been proposed.
Further, in order to improve sensation upon use, a cosmetic material formulated with a diester of cyclohexanedicarboxylic acid and polyoxyethylene monoalkyl ether (Patent Literature 4), and a cosmetic material including hair conditioners, etc. that is formulated with polyoxyethylene dicarboxylate ester (Patent Literature 5), and a hair cosmetic material formulated with dialkylene glycol monoalkyl ether (Patent Literature 6) have been proposed.
However, in any of the above Patent Literatures, the oil-based hair cosmetic material of the present invention comprising a specific dibasic acid ester compound and a specific oil agent has not been disclosed; in addition, any of the cosmetic materials disclosed in the above Patent Literatures have not been sufficiently investigated or confirmed in terms of their effects as a hair cosmetic material from the viewpoints of both the care for damaged hair and improvement in sensation upon use.
In Patent Literature 7, an invention of oil agents and others comprising a specific dibasic acid ester compound has been disclosed, and a composition comprising said oil agent has been described; however, the structure and application of this invention relate to an aqueous cosmetic, and the object of the invention is to improve the sensation of use upon application to skin. Thus, the structure, application, object and effects of the invention differ from those in the present invention. There is also no description or suggestion regarding the effects of the oil-based hair cosmetic material used in the present invention that comprises a specific dibasic acid ester compound and a specific oil agent.
As mentioned above, to date there is no oil-based hair cosmetic materials that can improve surface and internal conditions of damaged hair and add strength to the hair, with comfortable sensation upon use by achieving a non-sticky and light finish, and there is no oil-based hair cosmetic materials that enable the production of hair cosmetics having such effects. In other words, at present, hair cosmetic materials that provide excellent care for damaged hair tend to have inferior sensation upon use.
Accordingly, the development of technology and products to realize hair cosmetic materials having both superior improving effects on damaged hair and excellent sensation upon use has been strongly desired.